MusicIP Mixer (formerly MusicMagic) and its plugins otherwise known as MyDJ probably create(d) the best mixes based on a seed song that I've ever seen. It used to be bundled with WinAmp, which was how I discovered it. Pandora is pretty good but its coverage isn't always as good- MusicIP will process previously unknown songs algorithmically. The company was taken over or rebranded as AmpliFIND and provides its music processing services proprietarily (is that a word?). Downloads are still available on their website however since it's officially unsupported, I'm not sure how long that will be for.
Thus, you can download both the standalone mixer (which also scrobbles to last.fm and will send playlists to other players) as well as the plugins here.
Zemanta is a service that analyses your blog posts and suggests links (eg to wikipedia, imdb, etc) as well as related content and tags. Windows Live Writer, which unfortunately hasn't been updated since 2011 is one of the few blogging programs that supports multiple platforms such as Wordpress, Blogger, Typepad and LiveJournal. Zemanta used to support LJ but doesn't anymore, sadly. The Zemanta plugin for WLW is also no longer supported or available from its website but you can still find it mirrored here and here. You can imagine that it's pretty useful, even though as a plugin it doesn't support recommended tags.
So I've decided to mirror it here.